Generally, an air conditioner serves to maintain an indoor room as a comfortable state by maintaining an indoor temperature as a set temperature. The air conditioner comprises a refrigerating system. The refrigerating system comprises a compressor for compressing a refrigerant, a condenser for condensing a refrigerant compressed by the compressor and emitting heat outwardly, an expansion valve for lowering a pressure of a refrigerant condensed by the condenser, and an evaporator for evaporating a refrigerant that has passed through the expansion valve and absorbing external heat.
In the refrigerating system, when a compressor is operated as power is supplied thereto, a refrigerant of a high temperature and a high pressure discharged from the compressor sequentially passes through the condenser, the expansion valve, and the evaporator, and then is sucked into the compressor. The above process is repeated. In the above process, the condenser generates heat and the evaporator generates cool air by absorbing external heat. The heat generated from the condenser and the cool air generated from the evaporator are selectively circulated into an indoor room, thereby maintaining the indoor room as a comfortable state.
A compressor constituting the refrigerating system is various. Especially, a compressor applied to an air conditioner includes a rotary compressor, a scroll compressor, etc.
The most important factor in fabricating the air conditioner is to minimize a fabrication cost for a product competitiveness and to minimize a power consumption.
Especially, as an amount of oil usage is being increased worldwide, oil price is increased. Therefore, it is an important task to research an air conditioner to minimize a power consumption.
In order to minimize the power consumption of the air conditioner, the air conditioner is driven according to a load of an indoor room where the air conditioner is installed, that is, a temperature condition. That is, when the indoor temperature is drastically increased, the air conditioner is in a power mode so as to generate much cool air according to the drastic temperature variance (an excessive load). On the contrary, when the indoor temperature is varied with a small width, the air conditioner is in a saving mode so as to generate less cool air to maintain a preset indoor temperature.
In order to implement the modes, an amount of a refrigerant compressed by the compressor and discharged is controlled thereby to vary a refrigerating capacity of the refrigerating system.
As a method for controlling the amount of a refrigerant discharged from the compressor, an inverter motor is applied to the compressor thereby to vary an rpm of a driving motor of the compressor. An rpm of the driving motor of the compressor is controlled according to a load of an indoor room where the air conditioner is installed, and thus an amount of a refrigerant discharged from the compressor is controlled. An amount of heat generated from the condenser and cool air generated from the evaporator is controlled by varying the amount of a refrigerant discharged from the compressor.
However, in case of applying the inverter motor to the compressor, a fabrication cost is increased due to high price of the inverter motor thereby to degrade a price competitiveness.